package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollectionUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {

    @Resource
    private IUserService userService;

    @Resource
    private IFollowService followService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog -> {
            this.queryBlogUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result queryBlogById(Long id) {
        //1.查询blog
        Blog blog = getById(id);
        if (blog == null) {
            return Result.fail("笔记不存在！");
        }
        //2.查询blog有关的用户
        queryBlogUser(blog);
        //3.查询blog是否被当前用户点赞
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    private void isBlogLiked(Blog blog) {
        //1.获取当前用户
        UserDTO user = UserHolder.getUser();
        if (user == null) {
            //用户未登录，无需查询是否点赞
            return;
        }
        Long userId = user.getId();
        //2.判断当前用户是否已经点赞
        String key = RedisConstants.BLOG_LIKE_KEY + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    }

    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }

    @Override
    public Result likeBlog(Long id) {
        //1.获取当前用户
        Long userId = UserHolder.getUser().getId();
        //2.判断当前用户是否已经点赞
        String key = RedisConstants.BLOG_LIKE_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        //3.如果未点赞，可以点赞
        if (score == null) {
            //3.1 数据库点赞数 + 1
            boolean isSuccess = lambdaUpdate().setSql("liked = liked + 1").eq(Blog::getId, id).update();
            //3.2 保存用户ID到Redis的set集合 zadd key value scores
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            }
        } else {
            //4.如果已点赞，取消点赞
            //4.1 数据库点赞数 - 1
            boolean isSuccess = lambdaUpdate().setSql("liked = liked - 1").eq(Blog::getId, id).update();
            //4.2 把用户ID从Redis的set集合移除
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        return Result.ok();
    }

    @Override
    public Result queryBlogLikes(Long id) {
        String key = RedisConstants.BLOG_LIKE_KEY + id;
        //1.查询top5的点赞用户 zrange key 0 4
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (CollectionUtil.isEmpty(top5)) {
            return Result.ok(Collections.emptyList());
        }
        //2.解析出其中的用户id
        List<Long> userIds = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        //3.根据用户id查询用户
        //保证查出的顺序和传入的id顺序相同
        //WHERE id IN(5, 1) ORDER BY FIELD(id, 5, 1)
        //将id集合以逗号分隔形式拼接起来
        //String userIdStr = StrUtil.join(",", userIds);
        String userIdStr = userIds.stream().map(String::valueOf).collect(Collectors.joining(","));
        List<User> users = userService.lambdaQuery()
                .in(User::getId, userIds)
                .last(" ORDER BY FIELD(id, " + userIdStr + ")")
                .list();
        //将users进行封装
        List<UserDTO> userDTOS = BeanUtil.copyToList(users, UserDTO.class);
        //4.返回
        return Result.ok(userDTOS);
    }

    @Override
    public Result saveBlog(Blog blog) {
        //1.获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        //2.保存探店博文
        boolean isSuccess = save(blog);
        if (!isSuccess) {
            return Result.fail("新增笔记失败!");
        }
        //3.查询笔记作者的所有粉丝 select * from tb_follow where follow_user_id = ?
        List<Follow> follows = followService.lambdaQuery().eq(Follow::getFollowUserId, user.getId()).list();
        if (!follows.isEmpty()) {
            //4.推送笔记id给所有粉丝
            //新增笔记的时间戳
            long publishBlogTime = System.currentTimeMillis();
            for (Follow follow : follows) {
                //4.1 获取粉丝id
                Long userId = follow.getUserId();
                //4.2 推送
                String key = RedisConstants.FEED_KEY + userId;
                stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), publishBlogTime);
            }
        }
        // 返回id
        return Result.ok(blog.getId());
    }

    @Override
    public Result queryBlogFollowOfFollow(Long max, Integer offset) {
        //1.获取登录用户
        Long userId = UserHolder.getUser().getId();
        //2.查询收件箱 ZREVRANGEBYSCORE key max min withscores LIMIT offset count
        String key = RedisConstants.FEED_KEY + userId;
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 3);
        if (CollectionUtil.isEmpty(typedTuples)) {
            return Result.ok();
        }
        //3.解析数据：blogId、score(时间戳)、offset
        List<Long> idList = new ArrayList<>(typedTuples.size());
        long minTime = 0;
        //偏移量 初始为1
        int os = 1;
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples) {
            //3.1 获取id
            idList.add(Long.valueOf(tuple.getValue()));
            //3.2 获取分数
            long time = tuple.getScore().longValue();
            if (time == minTime) {
                os++;
            } else {
                minTime = time;
                os = 1;
            }
        }
        //4.根据blogId查询blog完整信息
//        String idStr = StrUtil.join(",", idList);
        String idStr = idList.stream().map(String::valueOf).collect(Collectors.joining(","));
        List<Blog> blogList = lambdaQuery()
                .in(Blog::getId, idList)
                .last(" ORDER BY FIELD(id, " + idStr + ")")
                .list();
        for (Blog blog : blogList) {
            //4.2 查询blog有关的用户
            queryBlogUser(blog);
            //4.3 查询blog是否被当前用户点赞
            isBlogLiked(blog);
        }
        //5.封装并返回
        ScrollResult scrollResult = new ScrollResult();
        scrollResult.setList(blogList);
        scrollResult.setOffset(os);
        scrollResult.setMinTime(minTime);
        return Result.ok(scrollResult);
    }
}
